CN110277961B - Photovoltaic string fault detection method and device - Google Patents
Photovoltaic string fault detection method and device Download PDFInfo
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Abstract
The invention provides a method and a device for detecting faults of photovoltaic strings, which utilize the current of the same photovoltaic string on a time sequence as a judgment basis, and reduce the false alarm rate of the faults. Meanwhile, transient faults caused by weather factors (such as cloud layer shielding) can be effectively eliminated by using the current deviation rate as a fault judgment basis, and the fault detection accuracy rate is improved. Moreover, since the large-level current (such as the total current of the bus device) is the sum of the small-level currents (such as the string current), and is easily influenced by other factors, the fault detection speed can be increased by adopting the judgment sequence of the currents from small to large. Meanwhile, the accuracy of fault detection can be improved by adopting a mode of multiple detection from small to large of current.
Description
Technical Field
The invention belongs to the technical field of photovoltaic power generation, and particularly relates to a method and a device for detecting faults of a photovoltaic string.
Background
The photovoltaic string is a core component in a photovoltaic power generation system, and is obtained by connecting a plurality of photovoltaic modules in series and/or in parallel.
Faults such as splinting, line aging, hot spots and the like of the photovoltaic module can occur, and the current photovoltaic string fault detection methods mainly comprise an infrared image detection method, an electric signal detection method, an event correlation detection method and a sensor-based detection method. However, the current fault detection method cannot quickly and accurately locate the failed photovoltaic string, and cannot accurately identify the occlusion shadow, which results in low detection accuracy.
Disclosure of Invention
In view of the above, the present invention provides a method and an apparatus for detecting a fault of a photovoltaic string, so as to solve the technical problems of a current fault detection method, such as low speed and low accuracy.
In a first aspect, the present invention provides a method for detecting a fault of a photovoltaic string, including:
acquiring a preset number of string currents of photovoltaic strings to be detected, which are acquired in a specified time window;
judging whether the photovoltaic string to be detected is abnormal or not according to the current of the preset number of strings;
when the photovoltaic string to be detected is determined to be abnormal, calculating a current deviation rate corresponding to the moment when the photovoltaic string to be detected is abnormal;
if the photovoltaic string to be detected is determined to be abnormal according to the current deviation rate, calculating a confluence total current deviation rate corresponding to the total current of each photovoltaic string connected with the confluence device connected with the photovoltaic string to be detected at the moment when the photovoltaic string to be detected is abnormal;
and if the total current deviation rate of the confluence is greater than a threshold value, determining that the photovoltaic string to be detected has a fault.
Optionally, the determining, according to the preset number of string currents, whether the photovoltaic string to be detected is abnormal includes:
calculating local abnormal factor values corresponding to the preset number of group string currents based on an outlier detection algorithm;
calculating the logarithm value of the local abnormal factor value corresponding to the preset number of group string currents;
if the logarithm value is larger than 1, determining that the photovoltaic string to be detected is abnormal in the appointed time window;
and if the logarithm value is less than or equal to 1, determining that the photovoltaic string to be detected is normal in the specified time window.
Optionally, after it is determined that the photovoltaic string to be detected is abnormal, calculating a current deviation rate corresponding to a moment when the photovoltaic string to be detected is abnormal, including:
when the photovoltaic string to be detected is determined to be abnormal, acquiring a string current corresponding to the abnormal moment of the photovoltaic string to be detected;
and calculating to obtain the current deviation rate according to the corresponding string current when the photovoltaic string to be detected is abnormal and the average value of the string current of the photovoltaic string to be detected at the same moment on the historical day.
Optionally judging whether the current deviation rate is greater than the threshold value, and if the current deviation rate is greater than the threshold value, determining that the photovoltaic string to be detected is abnormal; and if the current deviation rate is smaller than or equal to the threshold value, determining that the photovoltaic string to be detected is normal.
Optionally, if it is determined that the photovoltaic string to be detected is abnormal according to the current deviation rate, calculating a total current deviation rate of the junction corresponding to the total current of each photovoltaic string connected to the junction device connected to the photovoltaic string to be detected at the moment when the photovoltaic string to be detected is abnormal, including:
when the photovoltaic string to be detected is determined to be abnormal according to the current deviation rate, obtaining the sum of currents of all photovoltaic strings connected with the confluence device connected with the photovoltaic string to be detected at the moment when the photovoltaic string to be detected is abnormal, and obtaining the total current;
and calculating to obtain the total current deviation rate of the confluence according to the total current and the average value of the sum of the series currents of each group corresponding to the confluence device at the same time on the historical day.
Optionally, after determining that the photovoltaic string to be detected has a fault, the method further includes: and outputting alarm information.
Optionally, after determining that the photovoltaic string to be detected is normal within the specified time window, the method further includes:
and moving the designated time window backwards for a preset time length so that the number of the string currents of the photovoltaic string to be detected, which can be collected in the backward-translated designated time window, is the preset number.
Optionally, the method further comprises:
and when the number of the string currents of the photovoltaic string to be detected, which is collected in the appointed time window, is less than the preset number, increasing the duration of the appointed time window until the number of the string currents of the photovoltaic string to be detected, which is collected in the adjusted appointed time window, is equal to the preset number.
In a second aspect, the present invention further provides a photovoltaic string fault detection apparatus, including:
the acquisition module is used for acquiring preset quantity of string currents of the photovoltaic strings to be detected, which are acquired in a specified time window;
the judging module is used for judging whether the photovoltaic string to be detected is abnormal or not according to the current of the preset number of strings;
the first deviation rate calculation module is used for calculating a current deviation rate corresponding to the abnormal moment of the photovoltaic string to be detected after the abnormality of the photovoltaic string to be detected is determined;
the second deviation rate calculation module is used for calculating the convergence total current deviation rate corresponding to the total current of each photovoltaic group string connected with the convergence device connected with the photovoltaic group string to be detected at the moment when the abnormality of the photovoltaic group string to be detected occurs according to the current deviation rate when the abnormality of the photovoltaic group string to be detected is determined;
and the determining module is used for determining that the photovoltaic string to be detected has a fault when the total current deviation rate of the confluence is greater than a threshold value.
Optionally, the determining module includes:
the first calculation submodule is used for calculating local abnormal factor values corresponding to the preset number of string currents based on an outlier detection algorithm;
the second calculation submodule is used for calculating the logarithm value of the local abnormal factor value corresponding to the preset number of string currents;
the first determining submodule is used for determining that the photovoltaic group string to be detected is abnormal in the appointed time window when the logarithm value is larger than 1;
and the second determining submodule is used for determining that the photovoltaic group string to be detected is normal in the appointed time window when the logarithm value is less than or equal to 1.
According to the photovoltaic string fault detection method provided by the invention, whether the photovoltaic string is abnormal or not is preliminarily judged by using the currents of the same photovoltaic string at different moments. If the photovoltaic string is judged to be abnormal preliminarily, calculating the current deviation rate of the photovoltaic string, and judging whether the photovoltaic string is abnormal or not according to the current deviation rate; and if the photovoltaic string is judged to be abnormal according to the current deviation rate, continuously calculating the total current deviation rate of the total current of the convergence devices connected with the whole photovoltaic string, and finally determining whether the photovoltaic string has a fault. The method utilizes the current of the same photovoltaic group string on a time sequence as a judgment basis, and reduces the false alarm rate of faults. Meanwhile, transient faults caused by weather factors (such as cloud layer shielding) can be effectively eliminated by using the current deviation rate as a fault judgment basis, and the fault detection accuracy rate is improved. Moreover, since the large-level current (such as the total current of the bus device) is the sum of the small-level currents (such as the string current), and is easily influenced by other factors, the fault detection speed can be increased by adopting the judgment sequence of the currents from small to large. Meanwhile, the accuracy of fault detection can be improved by adopting a mode of multiple detection from small to large of current.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a photovoltaic string fault detection system according to an embodiment of the present invention;
fig. 2 is a flowchart of a method for detecting a fault of a photovoltaic string according to an embodiment of the present invention;
fig. 3 is a flowchart for determining whether a photovoltaic string is abnormal based on an outlier detection algorithm according to an embodiment of the present invention;
fig. 4 is a flowchart of a method for detecting a fault of a photovoltaic string according to an embodiment of the present invention;
fig. 5 is a block diagram of a photovoltaic string fault detection apparatus provided in an embodiment of the present invention;
fig. 6 is a block diagram of another photovoltaic string fault detection apparatus provided in an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, a schematic structural diagram of a photovoltaic string fault detection system provided in an embodiment of the present invention is shown, and as shown in fig. 1, the system includes a service server, a database, and a photovoltaic string; wherein, be provided with data acquisition device on every photovoltaic group cluster.
One photovoltaic group string is formed by connecting a plurality of photovoltaic modules in series and/or in parallel; a plurality of photovoltaic groups are connected in series-parallel and/or series to form a photovoltaic array.
In one embodiment of the invention, data is read from the cache database faster than the persistent database, and thus, the databases in the system may include both the persistent database (e.g., Mysql database) and the cache database (e.g., Memcached database). The service server can directly read data from the buffer database to improve the data reading speed and further improve the fault detection speed.
The data acquisition device acquires operation data of the photovoltaic string, such as current, voltage and the like, and transmits the acquired operation data to the service server. And the service server stores the operation data of each photovoltaic group string in the system into a database. When fault detection is needed, the service server reads the operation data of the photovoltaic group string to be detected from the database and executes a corresponding fault detection method.
In addition, the system also realizes the checking of the position information of each device and the positioning of the failed photovoltaic string by utilizing a GPS positioning system, and after the service server judges the failed photovoltaic string, the service server sends the position information of the failed string to the mobile terminal, thereby displaying the specific position of the failed string on the mobile terminal.
The following describes in detail a process of the service server for detecting a fault of the photovoltaic string.
Referring to fig. 2, a flowchart of a method for detecting a fault of a photovoltaic string according to an embodiment of the present invention is shown, where the method is applied to a service server in the system shown in fig. 1. As shown in fig. 2, the method may include the steps of:
and S110, acquiring a preset number of string currents of the photovoltaic string to be detected, which are acquired in a specified time window.
The photovoltaic string to be detected is any one photovoltaic string in the photovoltaic power generation system.
Each photovoltaic group string in the photovoltaic system has a unique identifier, and when the operation data of the photovoltaic group string is stored in the database, the unique identifier corresponding to the photovoltaic group string is correspondingly stored. And searching the operation data corresponding to the photovoltaic string from the database according to the unique identifier of the photovoltaic string. In this embodiment, the operation data of the photovoltaic string is mainly current data.
In this embodiment, the string currents corresponding to the same photovoltaic string at different times need to be obtained, for example, the string currents of the same photovoltaic string within a certain specified time window.
The time length of the designated time window can be set according to actual requirements, and the accuracy of the detection result is higher after the number of the string currents reaches the preset number, so that the setting of the designated time window needs to ensure that the same photovoltaic string contains the preset number of string current data in the designated time window.
The preset number may be determined according to a specific algorithm, for example, 20.
And S120, judging whether the photovoltaic string to be detected is abnormal or not according to the current of the preset number of strings. If the abnormality exists, executing S130; if there is no abnormality, S160 is executed.
In an embodiment of the present invention, whether the photovoltaic string to be detected is abnormal may be determined based on the outlier detection algorithm and according to the preset number of string currents in the specified time window, as shown in fig. 3, the specific determination process is as follows:
and S121, calculating LOF (local abnormal factor) values corresponding to the preset number of group string currents based on an outlier detection algorithm.
The outlier detection algorithm may be a LOF algorithm, which determines whether each point p is an abnormal point by comparing the density of the point with the density of the field point, and if the density of the point p is lower, the more likely the point p is an abnormal point. Wherein the density is calculated by the distance between the points, and the farther the distance between the points is, the lower the density is; the closer the distance between the dots, the higher the density. The LOF algorithm calculates the density by calculating the k distance of points in the domain, not by calculating the whole situation.
In this embodiment, for a preset number of group string currents within a set time window, an LOF value is calculated by using an LOF algorithm, and whether abnormal points exist in the group string currents can be determined according to the LOF value.
In this embodiment, the k distance may be set as a mean value of distances from the k neighboring points to the central point.
And S122, calculating logarithmic values of LOF values corresponding to the preset number of group current.
Because the calculated LOF value may be relatively large, the lg calculation is performed on the LOF value, and after the lg calculation is performed, the absolute numerical value of data can be reduced, and the calculation amount is reduced.
S123, judging whether the logarithm value is larger than 1; if the logarithm value is greater than 1, perform S124; if the logarithmic value is less than or equal to 1, S125 is performed.
The LOF value calculated according to the LOF algorithm is smaller than 1, which indicates that the density of the point is higher than that of the neighborhood point, and the point is a dense point; if the LOF value is greater than 1, it indicates that the density of the point is less than that of its field point, the point may be an outlier.
After lg operation is carried out on the LOF value, the lgLOF is less than 0, which indicates that the point is a dense point; a larger lgLOF value than 0 indicates that the point is an abnormal point. However, considering that the current data of the photovoltaic string also decreases when the cloud layer is shielded, but the drift speed of the cloud layer is relatively high, and the current of the photovoltaic string rapidly rises, the situation is not considered to be an abnormal situation, and therefore the judgment standard is amplified from 0 to 1.
And S124, determining that the photovoltaic string S124 to be detected is abnormal.
And if lgLOF is more than 1, determining that the photovoltaic string to be detected is abnormal.
And S125, determining that the photovoltaic string to be detected is normal.
And if lgLOF is less than or equal to 1, determining that the photovoltaic string to be detected is normal. And continuously judging whether the string current at the next moment of the photovoltaic string is abnormal or not.
And S130, calculating the current deviation rate corresponding to the abnormal moment of the photovoltaic string to be detected.
And after determining that the photovoltaic string to be detected is abnormal according to the lgLOF value, continuously calculating the current deviation rate corresponding to the abnormal moment of the photovoltaic string to be detected.
In one embodiment of the invention, after determining that the photovoltaic string to be detected is abnormal, acquiring a string current corresponding to the abnormal moment of the photovoltaic string to be detected; and calculating to obtain a current deviation rate according to the corresponding string current when the photovoltaic string to be detected is abnormal and the average value of the string current of the photovoltaic string to be detected at the same moment in the historical day.
In one possible implementation, the current deviation ratio is calculated as shown in equation 1:
BIAS ═ 100% (formula 1) (I1-I2)/I2)
In formula 1, BIAS is a current deviation rate, I1 is a string current corresponding to a time when a photovoltaic string to be detected is abnormal, and I2 is a string current average value corresponding to the same time on historical N days.
The N value is larger, the accuracy of the calculated current deviation rate is higher, and conversely, the accuracy of the calculated current deviation rate is lower when the N value is smaller. For example, N is set to 6, 12, 24, etc.
The same time refers to the same time as the abnormal time of the photovoltaic string to be detected in one day.
For example, the photovoltaic string to be detected is 14:00 out of 1 month and 10 daysWhen the current is abnormal, if N is 6, the string currents corresponding to the same time on the historical N days are the string currents I of the photovoltaic string to be detected 14:00 on 1 month, 4 days and 4 days respectively211 month, 5 days, 14:00 group current I221 month, 6 days, 14:00 group string current I231 month, 7 days, 14:00 group string current I241 month, 8 days, 14:00 group current I251 month, 9 days, 14:00 group current I26. Wherein I2 is I21、I22、I23、I24、I25、I26Average value of (a).
The larger the current deviation rate is, the more possible abnormality of the photovoltaic string exists; the smaller the current deviation rate, the more likely the photovoltaic string is to be normal.
And S140, if the photovoltaic string to be detected is determined to be abnormal according to the current deviation rate, calculating the total current deviation rate corresponding to the total current of each photovoltaic string connected with the confluence device connected with the photovoltaic string to be detected at the moment when the photovoltaic string to be detected is abnormal.
If the photovoltaic string to be detected is determined to be abnormal actually according to the deviation rate of the string current corresponding to the moment when the photovoltaic string to be detected is abnormal, the current deviation rate of the sum of the currents of all the branches in the junction device connected with the photovoltaic string to be detected, namely the total junction current deviation rate of the junction device, is continuously calculated.
The bus device is used for collecting the direct current of the photovoltaic group strings together and outputting the direct current to the inverter through a direct current bus. Each string of photovoltaic strings connected in a busbar arrangement is referred to as a branch.
The step is to calculate the deviation rate of the total current of the confluence device connected with the photovoltaic group string to be detected, and the deviation rate is called the total current deviation rate of confluence. Wherein the total current deviation rate of the bus is calculated in the same manner as the current deviation rate of the string current.
For example, the total current of the junction device where the photovoltaic string to be detected is located is obtained at the moment when the photovoltaic string to be detected is abnormal; then, the average value of the total current of the current collecting device at the same time in the historical N days is determined.
If the photovoltaic string to be detected is judged to be abnormal according to the current deviation rate of the photovoltaic string to be detected, whether the string current at the next moment of the photovoltaic string to be detected is abnormal is continuously judged, specifically, the set time window is translated backwards for a preset time length, namely, the string current data queue obtained based on the set time window is moved backwards for one bit of data, and then, whether the photovoltaic string to be detected is abnormal is continuously judged according to the moved string current data.
S150, if the total current deviation rate of the confluence is larger than a threshold value, determining that the photovoltaic string to be detected has a fault.
And if the deviation rate of the total current of the confluence is greater than the threshold value, determining that the photovoltaic string to be detected has a fault, and further, in order to enable maintenance personnel to eliminate the fault as soon as possible, sending alarm information after determining the photovoltaic string with the fault.
And if the deviation rate of the total current of the confluence is less than or equal to the threshold, determining that the photovoltaic string to be detected is normal, and not sending alarm information. And then, shifting the appointed time window backwards for a preset time, namely moving the string current data queue obtained based on the appointed time window backwards by one bit of data, and continuously judging whether the photovoltaic string to be detected is abnormal or not according to the moved string current data.
And S160, moving the appointed time window backwards for a preset time length. Then, execution returns to S120.
The preset duration may be a time interval at which the data acquisition device acquires the operating data of the photovoltaic string, for example, the data acquisition device acquires data every 1min, and then the time window may be translated backwards for 1 min. Namely, the designated time window is moved backwards by one bit of data, namely, the data with the earliest acquisition time is deleted, and the data corresponding to the next time of the latest time of the designated time window is added, so that the data in the designated time window is ensured to be in a preset number.
According to the photovoltaic string fault detection method provided by the invention, whether the photovoltaic string is abnormal or not is preliminarily judged by using the currents of the same photovoltaic string at different moments. If the photovoltaic string is judged to be abnormal preliminarily, calculating the current deviation rate of the photovoltaic string, and judging whether the photovoltaic string is abnormal or not according to the current deviation rate; and if the photovoltaic string is judged to be abnormal according to the current deviation rate, continuously calculating the total current deviation rate of the total current of the convergence devices connected with the whole photovoltaic string, and finally determining whether the photovoltaic string has a fault. The method utilizes the current of the same photovoltaic group string on a time sequence as a judgment basis, and reduces the false alarm rate of faults. Meanwhile, transient faults caused by weather factors (such as cloud layer shielding) can be effectively eliminated by using the current deviation rate as a fault judgment basis, and the fault detection accuracy rate is improved. Moreover, since the large-level current (such as the total current of the bus device) is the sum of the small-level currents (such as the string current), and is easily influenced by other factors, the fault detection speed can be increased by adopting the judgment sequence of the currents from small to large. Meanwhile, the accuracy of fault detection can be improved by adopting a mode of multiple detection from small to large of current.
Referring to fig. 4, a flowchart of another method for detecting a fault of a photovoltaic string according to an embodiment of the present invention is shown, where the embodiment further includes the following steps based on the embodiment shown in fig. 1:
and S210, when the number of the string currents of the photovoltaic string to be detected, which are collected in the appointed time window, is less than the preset number, increasing the duration of the appointed time window until the number of the string currents of the photovoltaic string to be detected, which are collected in the adjusted appointed time window, is equal to the preset number.
Before the method is executed, the time length of a specified time window needs to be set, then, the string current of the photovoltaic string to be detected in the specified time window is obtained, and the time length of the specified time window is set, considering that the accuracy of an outlier detection algorithm is low when the data volume is small, so that the time length of the specified time window needs to ensure that the specified time window contains a preset number of string currents.
And if the number of the group string currents contained in the set time window is smaller than the preset number, increasing the duration of the specified time window until the number of the group string currents contained in the specified time window reaches the preset number.
According to the photovoltaic string fault detection method provided by the embodiment, the current of the same photovoltaic string on a time sequence is used as a judgment basis, so that the false alarm rate of the fault is reduced. Meanwhile, transient faults caused by weather factors (such as cloud layer shielding) can be effectively eliminated by using the current deviation rate as a fault judgment basis, and the fault detection accuracy rate is improved. Moreover, since the large-level current (such as the total current of the bus device) is the sum of the small-level currents (such as the string current), and is easily influenced by other factors, the fault detection speed can be increased by adopting the judgment sequence of the currents from small to large. Meanwhile, the accuracy of fault detection can be improved by adopting a mode of multiple detection from small to large of current.
Corresponding to the embodiment of the photovoltaic string fault detection method, the invention also provides an embodiment of a photovoltaic string fault detection device.
Referring to fig. 5, a block diagram of a photovoltaic string fault detection apparatus provided in an embodiment of the present invention is shown, where the apparatus is applied in a server. As shown in fig. 5, the apparatus includes: the system comprises an acquisition module 110, a first judgment module 120, a first deviation ratio calculation module 130, a second deviation ratio calculation module 140 and a determination module 150.
The obtaining module 110 is configured to obtain a preset number of string currents of the to-be-detected photovoltaic string collected within a specified time window.
The judging module 120 is configured to judge whether the photovoltaic string to be detected is abnormal according to the preset number of string currents.
In an embodiment of the present invention, whether the photovoltaic string to be detected is abnormal may be determined based on an outlier detection algorithm according to a preset number of string currents within a specified time window. Specifically, the judging module includes: the device comprises a first calculation submodule, a second calculation submodule, a first determination submodule and a second determination submodule;
and the first calculating submodule is used for calculating LOF values corresponding to the preset number of group-string currents based on the outlier detection algorithm.
And the second calculating submodule is used for calculating logarithm values of LOF values corresponding to the preset number of group string currents.
And the first determining submodule is used for determining that the photovoltaic string to be detected has abnormity in the appointed time window when the logarithm value is larger than 1.
And the second determining submodule is used for determining that the photovoltaic group string to be detected is normal in a specified time window when the logarithm value is less than or equal to 1.
The first deviation ratio calculating module 130 is configured to calculate a current deviation ratio corresponding to a moment when the photovoltaic string to be detected is abnormal after the photovoltaic string to be detected is determined to be abnormal.
In one embodiment of the present invention, the first deviation ratio calculation module 130 includes: the device comprises an acquisition submodule and a first deviation ratio calculation submodule.
The first obtaining submodule is used for obtaining the string current corresponding to the abnormal moment of the photovoltaic string to be detected after the photovoltaic string to be detected is determined to be abnormal.
And the first deviation rate calculation submodule is used for calculating to obtain a current deviation rate according to the corresponding string current when the photovoltaic string to be detected is abnormal and the corresponding string current average value of the photovoltaic string to be detected at the same moment in the historical day.
After the current deviation rate corresponding to the abnormal moment of the photovoltaic string to be detected is obtained through calculation, whether the photovoltaic string to be detected is abnormal is further judged according to the current deviation rate, and the process of judging whether the photovoltaic string is abnormal according to the current deviation rate is as follows:
judging whether the current deviation rate is greater than a threshold value, and if the current deviation rate is greater than the threshold value, determining that the photovoltaic string to be detected is abnormal; and if the current deviation rate is smaller than or equal to the threshold value, determining that the photovoltaic string to be detected is normal.
The second deviation ratio calculating module 140 is configured to calculate, when it is determined that the photovoltaic string to be detected is abnormal according to the current deviation ratio, a total current deviation ratio corresponding to a total current of each photovoltaic string connected to the junction device connected to the photovoltaic string to be detected at a time when the photovoltaic string to be detected is abnormal.
In one embodiment of the present invention, the second deviation ratio calculation module 140 may include
And the second obtaining submodule is used for obtaining the sum of the currents of all the photovoltaic string strings connected with the confluence device connected with the photovoltaic string to be detected at the moment when the photovoltaic string to be detected is abnormal according to the current deviation rate, so as to obtain the total current.
And the second deviation rate calculation submodule is used for calculating the total current deviation rate of the confluence according to the total current and the average value of the sum of all groups of series currents corresponding to the confluence device at the same time on the historical day.
The determining module 150 is configured to determine that the photovoltaic string to be detected has a fault when the total current deviation rate is greater than the threshold.
If the deviation rate of the total current of the confluence is larger than a threshold value, determining that the photovoltaic string to be detected has a fault; and if the deviation rate of the total current of the confluence is less than or equal to the threshold value, determining that no fault exists in the photovoltaic string to be detected.
Optionally, as shown in fig. 6, a block diagram of another photovoltaic string fault detection apparatus provided in an embodiment of the present invention is further included on the basis of the embodiment shown in fig. 5:
the time window adjusting module 210 is configured to increase the duration of the designated time window when the number of the string currents of the to-be-detected photovoltaic string collected in the designated time window is smaller than the preset number, until the number of the string currents of the to-be-detected photovoltaic string collected in the adjusted designated time window is equal to the preset number.
The time window translation module 220 is configured to, after it is determined that the to-be-detected photovoltaic string is normal in the designated time window, move the designated time window backward for a preset time duration, so that the number of string currents of the to-be-detected photovoltaic string that can be collected in the backward-translated designated time window is a preset number.
And the alarm module 230 is configured to output alarm information after determining that the photovoltaic string to be detected has a fault.
The photovoltaic string fault detection device provided by the invention utilizes the current of the same photovoltaic string at different moments to preliminarily judge whether the photovoltaic string is abnormal or not. If the photovoltaic string is judged to be abnormal preliminarily, calculating the current deviation rate of the photovoltaic string, and judging whether the photovoltaic string is abnormal or not according to the current deviation rate; and if the photovoltaic string is judged to be abnormal according to the current deviation rate, continuously calculating the total current deviation rate of the total current of the convergence devices connected with the whole photovoltaic string, and finally determining whether the photovoltaic string has a fault. The device utilizes the current of the same photovoltaic group string on a time sequence as a judgment basis, and reduces the false alarm rate of faults. Meanwhile, transient faults caused by weather factors (such as cloud layer shielding) can be effectively eliminated by using the current deviation rate as a fault judgment basis, and the fault detection accuracy rate is improved. Moreover, since the large-level current (such as the total current of the bus device) is the sum of the small-level currents (such as the string current), and is easily influenced by other factors, the fault detection speed can be increased by adopting the judgment sequence of the currents from small to large. Meanwhile, the accuracy of fault detection can be improved by adopting a mode of multiple detection from small to large of current.
While, for purposes of simplicity of explanation, the foregoing method embodiments have been described as a series of acts or combination of acts, it will be appreciated by those skilled in the art that the present invention is not limited by the illustrated ordering of acts, as some steps may occur in other orders or concurrently with other steps in accordance with the invention. Further, those skilled in the art should also appreciate that the embodiments described in the specification are preferred embodiments and that the acts and modules referred to are not necessarily required by the invention.
It should be noted that, in the present specification, the embodiments are all described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments may be referred to each other. For the device-like embodiment, since it is basically similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
The steps in the method of the embodiments of the present application may be sequentially adjusted, combined, and deleted according to actual needs.
The device and the modules and sub-modules in the terminal in the embodiments of the present application can be combined, divided and deleted according to actual needs.
In the several embodiments provided in the present application, it should be understood that the disclosed terminal, apparatus and method may be implemented in other manners. For example, the above-described terminal embodiments are merely illustrative, and for example, the division of a module or a sub-module is only one logical division, and there may be other divisions when the terminal is actually implemented, for example, a plurality of sub-modules or modules may be combined or integrated into another module, or some features may be omitted or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or modules, and may be in an electrical, mechanical or other form.
The modules or sub-modules described as separate parts may or may not be physically separate, and parts that are modules or sub-modules may or may not be physical modules or sub-modules, may be located in one place, or may be distributed over a plurality of network modules or sub-modules. Some or all of the modules or sub-modules can be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
In addition, each functional module or sub-module in the embodiments of the present application may be integrated into one processing module, or each module or sub-module may exist alone physically, or two or more modules or sub-modules may be integrated into one module. The integrated modules or sub-modules may be implemented in the form of hardware, or may be implemented in the form of software functional modules or sub-modules.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A method for detecting a fault of a photovoltaic string is characterized by comprising the following steps:
acquiring a preset number of string currents of photovoltaic strings to be detected, which are acquired in a specified time window;
judging whether the photovoltaic string to be detected is abnormal or not according to the current of the preset number of strings;
when the photovoltaic string to be detected is determined to be abnormal, calculating a current deviation rate corresponding to the moment when the photovoltaic string to be detected is abnormal, wherein the current deviation rate represents the deviation degree between the string current of the photovoltaic string to be detected at the moment when the photovoltaic string to be detected is abnormal and the string current of the photovoltaic string at the same moment on the historical day;
if the photovoltaic string to be detected is determined to be abnormal according to the current deviation rate, calculating a total current deviation rate corresponding to total current of each photovoltaic string connected with the junction device connected with the photovoltaic string to be detected at the moment when the photovoltaic string to be detected is abnormal, wherein the total current deviation rate represents the junction device connected with the photovoltaic string to be detected, and the deviation degree between the total current at the moment when the photovoltaic string to be detected is abnormal and the total current at the same moment on the historical day;
and if the total current deviation rate of the confluence is greater than a threshold value, determining that the photovoltaic string to be detected has a fault.
2. The method according to claim 1, wherein the determining whether the photovoltaic string to be detected is abnormal according to the current of the preset number of strings comprises:
calculating local abnormal factor values corresponding to the preset number of group string currents based on an outlier detection algorithm;
calculating the logarithm value of the local abnormal factor value corresponding to the preset number of group string currents;
if the logarithm value is larger than 1, determining that the photovoltaic string to be detected is abnormal in the appointed time window;
and if the logarithm value is less than or equal to 1, determining that the photovoltaic string to be detected is normal in the specified time window.
3. The method according to claim 1, wherein after it is determined that the photovoltaic string to be detected is abnormal, calculating a current deviation rate corresponding to a time when the photovoltaic string to be detected is abnormal, includes:
when the photovoltaic string to be detected is determined to be abnormal, acquiring a string current corresponding to the abnormal moment of the photovoltaic string to be detected;
and calculating to obtain the current deviation rate according to the corresponding string current when the photovoltaic string to be detected is abnormal and the average value of the string current of the photovoltaic string to be detected at the same moment on the historical day.
4. The method according to claim 1, wherein determining whether the photovoltaic string to be detected is abnormal according to the current deviation rate comprises:
judging whether the current deviation rate is greater than a first threshold value, and if the current deviation rate is greater than the first threshold value, determining that the photovoltaic string to be detected is abnormal; and if the current deviation rate is smaller than or equal to the first threshold value, determining that the photovoltaic string to be detected is normal.
5. The method according to claim 1, wherein if it is determined that the photovoltaic string to be detected is abnormal according to the current deviation rate, calculating a total current deviation rate corresponding to a total current of each photovoltaic string connected to the junction device connected to the photovoltaic string to be detected at a time when the photovoltaic string to be detected is abnormal, includes:
when the photovoltaic string to be detected is determined to be abnormal according to the current deviation rate, obtaining the sum of currents of all photovoltaic strings connected with the confluence device connected with the photovoltaic string to be detected at the moment when the photovoltaic string to be detected is abnormal, and obtaining the total current;
and calculating to obtain the total current deviation rate of the confluence according to the total current and the average value of the sum of the series currents of each group corresponding to the confluence device at the same time on the historical day.
6. The method of claim 1, wherein after determining that the photovoltaic string to be tested has a fault, the method further comprises: and outputting alarm information.
7. The method of claim 2, wherein after determining that the string of photovoltaic groups to be detected is normal within the specified time window, the method further comprises:
and moving the designated time window backwards for a preset time length so that the number of the string currents of the photovoltaic string to be detected, which can be collected in the backward-translated designated time window, is the preset number.
8. The method of claim 1, further comprising:
and when the number of the string currents of the photovoltaic string to be detected, which is collected in the appointed time window, is less than the preset number, increasing the duration of the appointed time window until the number of the string currents of the photovoltaic string to be detected, which is collected in the adjusted appointed time window, is equal to the preset number.
9. A photovoltaic string fault detection device, comprising:
the acquisition module is used for acquiring preset quantity of string currents of the photovoltaic strings to be detected, which are acquired in a specified time window;
the judging module is used for judging whether the photovoltaic string to be detected is abnormal or not according to the current of the preset number of strings;
the first deviation rate calculating module is used for calculating a current deviation rate corresponding to the abnormal moment of the photovoltaic string to be detected after the abnormality of the photovoltaic string to be detected is determined, wherein the current deviation rate represents the deviation degree between the string current of the photovoltaic string to be detected at the abnormal moment and the string current of the photovoltaic string at the same moment in the historical day;
the second deviation rate calculation module is used for calculating a total current deviation rate corresponding to the total current of each photovoltaic group string connected with the junction device connected with the photovoltaic group string to be detected at the moment when the photovoltaic group string to be detected is abnormal according to the current deviation rate, wherein the total current deviation rate represents the junction device connected with the photovoltaic group string to be detected, and the deviation degree between the total current at the moment when the photovoltaic group string to be detected is abnormal and the total current at the same moment in the historical day;
and the determining module is used for determining that the photovoltaic string to be detected has a fault when the total current deviation rate of the confluence is greater than a threshold value.
10. The apparatus of claim 9, wherein the determining module comprises:
the first calculation submodule is used for calculating local abnormal factor values corresponding to the preset number of string currents based on an outlier detection algorithm;
the second calculation submodule is used for calculating the logarithm value of the local abnormal factor value corresponding to the preset number of string currents;
the first determining submodule is used for determining that the photovoltaic group string to be detected is abnormal in the appointed time window when the logarithm value is larger than 1;
and the second determining submodule is used for determining that the photovoltaic group string to be detected is normal in the appointed time window when the logarithm value is less than or equal to 1.
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| CN111402078B (en) * | 2020-03-11 | 2023-06-30 | 阳光新能源开发股份有限公司 | Photovoltaic string diagnosis method, device and controller |
| CN111882833B (en) * | 2020-07-21 | 2021-09-21 | 华润电力唐山丰润有限公司 | Equipment fault early warning method, device, equipment and medium based on outlier parameters |
| CN113985239A (en) * | 2021-10-13 | 2022-01-28 | 合肥阳光智维科技有限公司 | Method, device, equipment and storage medium for identifying faults of group string bypass diode |
| CN117424559B (en) * | 2023-10-20 | 2024-06-18 | 重庆千信新能源有限公司 | Method for monitoring photovoltaic coating power failure by using machine vision |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104779914A (en) * | 2015-04-28 | 2015-07-15 | 北京汉能光伏投资有限公司 | Conflux detection method and system for conflux boxes and solar power station |
| CN107222169A (en) * | 2017-08-01 | 2017-09-29 | 河海大学常州校区 | A kind of photovoltaic array based on outlier detection is monitored and fault detection method in real time |
| CN107395121A (en) * | 2017-08-01 | 2017-11-24 | 河海大学常州校区 | Based on Grubbs test method and outlier detection photovoltaic array fault detection method |
| CN107634719A (en) * | 2017-08-03 | 2018-01-26 | 华电电力科学研究院 | Centralized inverter scheme novel photovoltaic group string online system failure diagnosis and method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10243514B2 (en) * | 2015-06-04 | 2019-03-26 | Ryan Bower Jones | Photovoltaic soil monitoring system with automated clean referencing system |
-
2019
- 2019-06-18 CN CN201910539159.3A patent/CN110277961B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104779914A (en) * | 2015-04-28 | 2015-07-15 | 北京汉能光伏投资有限公司 | Conflux detection method and system for conflux boxes and solar power station |
| CN107222169A (en) * | 2017-08-01 | 2017-09-29 | 河海大学常州校区 | A kind of photovoltaic array based on outlier detection is monitored and fault detection method in real time |
| CN107395121A (en) * | 2017-08-01 | 2017-11-24 | 河海大学常州校区 | Based on Grubbs test method and outlier detection photovoltaic array fault detection method |
| CN107634719A (en) * | 2017-08-03 | 2018-01-26 | 华电电力科学研究院 | Centralized inverter scheme novel photovoltaic group string online system failure diagnosis and method |
Non-Patent Citations (1)
| Title |
|---|
| 一种光伏阵列实时状态监测与故障定位系统;韩付昌 等.;《福州大学学报（自然科学版）》;20181231;第46卷(第6期);全文 * |
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